Sample VIPA environment
The following sample VIPA environment with Ethernet connections involves a system with a virtual IP address and two physical connections.
A system has a virtual IP address, vi0,
of 10.68.6.1 and two physical connections, en1 with
IP address 10.68.1.1 and en5, with
IP address 10.68.5.1. In this example, both physical
connections are Ethernet, but any mixture of IP interfaces, such as
token-ring or FDDI, would be supported as long as the subnets were
ultimately attached to the larger corporate network and were known
to the corporate routers.
netaddr 10.68.6.1 N/A True
state up Standard Ethernet Network Interface True
netmask 255.255.255.0 Maximum IP Packet Size for This Device True
netaddr6 Maximum IP Packet Size for REMOTE Networks True
alias6 Internet Address True
prefixlen Current Interface Status True
alias4 TRAILER Link-Level Encapsulation True
interface_names en1,en5 Interfaces using the Virtual Address True vi0: flags=84000041<UP,RUNNING,64BIT>
inet 10.68.6.1 netmask 0xffffff00
iflist : en1 en5 Routing tables
Destination Gateway Flags Refs Use If PMTU Exp Groups
Route Tree for Protocol Family 2 (Internet):
default 10.68.1.2 UG 3 1055 en1 - -
10.68.1/24 10.68.1.1 U 0 665 en1 - -
10.68.5/24 10.68.5.1 U 0 1216 en5 - -
127/8 127.0.0.1 U 4 236 lo0 - -
10.68.6.1 127.0.0.1 UH 0 0 lo0 - - The
outgoing packets that do not have a source address set and that are
routed via interfaces en1 and en5 will
have the source address set to the virtual address (10.68.6.1).
Incoming packets are routed to the VIPA address (10.68.6.1)
advertised on the network. Because vi0 is virtual
(that is, not associated with any device) there should be no entries
for it in the system-wide routing table displayed using the netstat
-rn command. This means no interface route is added when
the interface is configured in SMIT.
If one of the physical
interfaces, a network attachment, or a network path fails, the network
protocols route to the other physical interface on the same system.
If a remote system telnets to the vi0 address, packets
to vi0 can arrive using either en1 or en5.
If en1 is down, for example, packets can still arrive
on en5. Note that routing protocols might take time
to propagate the routes.
When using the VIPA, the end systems
and intervening routers must be able to route the packets destined
for VIPA (vi0) to one of the physical interfaces
(en1 or en5).